Of course batteries can start a fire, they are full of acids and reactive metals, not to mention they can short circut all by themselves and get very hot. Especially batteries like laptop batteries where the + and - terminals are very close together? Hello.

Sounds like the batteries came into contact with something that they reacted with. Mabye UPS should pay more attention to charts like THIS when they pack their stupid airplanes full of stupidly reactive chemicals._________________"I reject your reality, and substitute my own!" - Adam Savage (MythBusters)
"I don't know the key to success, but the key to failure is trying to please everyone." - Bill Cosby